As communication technology advances, evolution of 3G mobile communication systems is about to reach their fourth generation (4G). Such a 4G mobile communication system enables mobile communication terminals capable of using mobile communication systems to be based on IP (Internet Protocol) in communication, and implement fast upload and download speeds.
Evolution for reaching the 4G mobile communication system contributes to sending/receiving user data even faster. On the contrary, mobile communication terminals are expected to consume more power to cause the available time for mobile communication terminals to be reduced.
Accordingly, there is a need for developing a method for improving battery life on mobile communication terminals in line with emerging 4G mobile communication systems.
The exemplary Green-T(echnology) of EUREKA project has studied the technology for minimizing power consumed by the 4G mobile communication terminals by adopting heterogeneous radio access technologies in order to overcome the aforementioned energy trap thereof.
In particular, the Green-T project aims to develop a method for implementing data communication by using a neighboring short-range wireless communication system if much transmission power is required for sending/receiving data to/from a base station because terminals are far away from the base station.
For example, FIG. 1 shows an exemplary system block using a wireless LAN or wireless PAN (Personal Area Network) for a mobile communication terminal with battery limitation in short-range wireless communication with other mobile communication terminals while the other mobile communication terminals use 4G mobile communication for relay to a base station.
The other mobile communication terminals may be a mobile communication terminal free from power consumption compared with the mobile communication terminal in the battery limitation.
FIG. 2 shows a system block for sending/receiving data to/from a mobile communication terminal by using a short-range wireless communication system, for example, a wireless LAN or high-speed wireless PAN, not 4G mobile communications.
The aforementioned FIGS. 1 and 2 illustrate reducing power consumption by utilizing a neighboring mobile communication terminal or neighboring short-range wireless communication system while adopting short-range wireless communication, not direct wireless communication through a base station.
Mobile communication terminals of which the battery levels is below a certain level and which do not consume enough power or have battery limitation utilize short-range wireless communication systems, for example, a wireless LAN or wireless PAN in place of using a base station in order to reduce power consumption, as shown in FIGS. 1 and 2. In this case, however, it is also necessary to discover a device for sending or receiving data by wire or wireless to/from a base station or a mobile communication control station for managing or working as the base station in a short-range wireless communication system in place of access to the base station of a mobile communication terminal.
In particular, if a short-range wireless communication system is used as shown in FIG. 1 or 2, it may adopt various radio access technologies. The aforementioned radio access technologies will be more diversified along with evolving communication technologies.
In addition, because there is a plurality of allocated frequencies in one and the same radio access technology, it is also necessary to determine which frequency to be used in one and the same radio access technology.
A mobile communication terminal of which the battery level is below a certain level needs to determine whether each radio access technology and each frequency used in the each radio access technology meet the service that the mobile communication terminal wants to use. Accordingly, there is a need for association for each radio access technology.
Therefore, for vertical handover of a mobile communication terminal of which the battery level is below a certain level, even more power is required to find an adapted technology from many radio access technologies.
As a result, there is a need for a method for discovering a radio access technology by a mobile communication terminal and a wireless access system to enable the mobile communication terminal to find the radio access technology the mobile communication terminal wants from a plurality of radio access technologies with even less power.